I used to worry excessively about aligning guides on or opposite the rod's spine (splines are something else, not rod related). Anyhow, as I began to use high quality blanks from Winston, Orvis, G. Loomis, etc, I found two things: First, it was getting harder and harder to find the damn spine; Second, the rod companies don't worry about it, they just put the guides where they'll pull the blank into its straightest alignment. As they began to use precision flag cutting equipment and blank rollers, blanks began to get better and better. Serious enough spine to affect casting is a defect--the better companies cull these blanks, or should, and their precision manufacturing methods should prevent these defects most of the time (even low end rod companies mostly use the same methods--one reason bargain rods are getting better). The same thing is true of bamboo. If your strips aren't virtually the same as the rest, they should be tossed in the fire--that's one reason most makers plane extras. So, if you're using the accepted techniques for finding the spine and it's not jumping out at you--literally--it might not be there.
CC